This Core provides essential research services to all three of the scientific projects of this Program. The Core is directed by Dr. Norman Fleischer. The function of this Core is to efficiently provide purified mouse islets, and physiological studies of beta-cell function. Projects 1, 2 and 3 will utilize mouse pancreatic islets in the performance of the proposed research. To provide this service, the production of mouse islets is centralized into a single facility and available to the Investigators of this program. Projects 1, 2 and 3 will utilize studies of islet and beta cell physiology. These studies will also be performed by this Core. Studies will include assessment of secretory function of isolated islets to determine their suitability for transplantation and to determine the effect of genetic manipulations as proposed in Project 2 on their function. Similar studies will also be done in human islets. Additionally, extensive physiological and biochemical studies of hepatic progenitor cells engineered to secrete insulin will be performed. Because Dr. Fleischer, the Core Director, has a central interest in insulin secretion and has in place these assays, it will be efficient to perfume these studies in a centralized core.